diff --git a/src/hnswbuild.c b/src/hnswbuild.c
index 2e44031..f5ea264 100644
--- a/src/hnswbuild.c
+++ b/src/hnswbuild.c
@@ -267,6 +267,9 @@ WriteNeighborTuples(HnswBuildState * buildstate)
 		/* Update iterator */
 		iter = e->next;
 
+		/* Zero memory for each element */
+		MemSet(ntup, 0, HNSW_TUPLE_ALLOC_SIZE);
+
 		/* Can take a while, so ensure we can interrupt */
 		/* Needs to be called when no buffer locks are held */
 		CHECK_FOR_INTERRUPTS();
diff --git a/src/hnswvacuum.c b/src/hnswvacuum.c
index fb8ec4f..71ccea5 100644
--- a/src/hnswvacuum.c
+++ b/src/hnswvacuum.c
@@ -208,6 +208,9 @@ RepairGraphElement(HnswVacuumState * vacuumstate, HnswElement element, HnswEleme
 	/* Find neighbors for element, skipping itself */
 	HnswFindElementNeighbors(base, element, entryPoint, index, procinfo, collation, m, efConstruction, true);
 
+	/* Zero memory for each element */
+	MemSet(ntup, 0, HNSW_TUPLE_ALLOC_SIZE);
+
 	/* Update neighbor tuple */
 	/* Do this before getting page to minimize locking */
 	HnswSetNeighborTuple(base, ntup, element, m);